PSI - Issue 39

O.N. Belova et al. / Procedia Structural Integrity 39 (2022) 770–785 Author name / Structural Integrity Procedia 00 (2021) 000–000

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Fig. 2 Test specimen: geometry of the cracked specimen and schematic presentation of the load.

Fig. 3. Digital images obtained from photoelastic measurement experiments: isochromatic images in the plate with two inclined parallel cracks subject to 90 kg, 95 kg and 100 kg. Isochromatic fringe patterns obtained for the plate with two cracks under different loads are shown in fig. 3. One can see from fig. 3 that it is not possible to provide an accurate description of the stress field in the vicinity of the crack tip considering the one-term asymptotic series expansion only. Fringe tracking and fringe order assignment have become the central topic of current research in digital photoelasticity (Ramesh and Sasikumar (2020)). The skeleton of the fringe is first identified to precisely gather the experimental data from the fringes. The program is especially devised for the interpretation and processing of experimental data from the photoelasticity measurement experiments. The invented and approved programming tool permits to find points that belong to isochromatic fringes with minimal light intensity. Data ( , , ) N r θ are collected from the stored digital image. The analysis of the experimental data uses a Java application programmed for the advanced determination of the fracture mechanics characteristics: coefficients of the Williams series expansion (WE) for the stress field in the vicinity of the crack tip. The programming tool allows us to gather experimental points from the photoelasticity tests on the cracked specimens. The skeleton of isochromatic